m = 9.1e-31;
e = -1.6e-19;
speedOfLight = 2.99792458e8; 
ramanShift = 150e-9;% source wavelength in m
freq =speedOfLight/ramanShift; 
magneticPermeability0 = 4.0 * pi * 1.0e-7;
electricalPermittivity0 = 1.0 / (speedOfLight * speedOfLight * magneticPermeability0);   
density  = m*electricalPermittivity0*4*pi*pi*freq*freq/e/e
nc = electricalPermittivity0*m/e/e*(2*pi*speedOfLight/800e-9)*(2*pi*speedOfLight/800e-9)
    